AQA GCSE Chemistry Key Words

Key Chemical Terms

• Acid: Low pH solution rich in hydrogen ions.
• Activation Energy: Minimum energy required to initiate a chemical reaction.
• Alkali: High pH solution containing hydroxide ions.
• Alkali Metals: Highly reactive metals located on the left of the periodic table.
• Alkanes: Hydrocarbons characterized by single bonds.
• Alkenes: Hydrocarbons with at least one double bond.
• Alloy: A mixture of metals that creates distorted atomic layers, preventing sliding.
• Anode: The positive electrode during electrolysis.
• Aqueous Solution: A solution that dissolves a substance in water.
• Atom: The basic unit of matter, composed of protons, neutrons, and electrons.
• Atomic Number: Represents the number of protons in an atom.
• Base: Metal oxides, hydroxides, or carbonates that react with acids to form salt.
• Biodegradable: Materials able to decompose through microbial action.
• Biofuel: Fuels produced from biological materials such as plants and animals.
• Bioleaching: Using bacteria to extract metals from low-grade ores.
• Blast Furnace: Industrial apparatus used to extract iron from its ore via complex chemical reactions.
• Bromine Water: Test agent (orange liquid) for detecting double bonds in organic compounds.
• Burette: Long glass tube with a tap for measuring liquid volumes.
• Carbon Footprint: Quantifies carbon emissions from everyday activities.
• Catalyst: A substance that accelerates a reaction without being consumed.
• Cathode: The negative electrode in electrolysis.
• Chromatography: Technique for separating dissolved substances via solvent movement on a medium.
• Collision Theory: Explains reactions as collisions between particles with adequate energy.
• Combustion: The process of burning a substance in the presence of oxygen.
• Compound: A substance formed from two or more chemically bonded elements.
• Covalent Bonding: The sharing of electron pairs between non-metals.
• Cracking: Process of breaking down long hydrocarbon chains into shorter chains.
• Crude Oil: Naturally occurring mixture of various-length hydrocarbons from decomposed organic matter.
• Desalination: The process of removing salt from water.
• Delocalised Electron: Electrons that are not tied to a single atom but are spread out across several atoms.
• Dependent Variable: The variable measured in response to changes in the independent variable.
• Diamond: A form of carbon with a tetrahedral lattice structure and four covalent bonds to each carbon atom.
• Diffusion: The spontaneous mixing of molecules due to random particle movement.
• Displacement Reaction: One element replaces another in a compound.
• Distillation: Method to separate liquids based on boiling points via evaporation and condensation.
• Electrolysis: The process of using electricity to separate compounds.
• Electrolyte: A conductive liquid containing free ions used in electrolysis.
• Electron: A negatively charged subatomic particle found in atomic shells, effectively massless.
• Element: A basic substance made up of atoms with identical properties, found on the periodic table.
• Endothermic Reaction: A chemical reaction that absorbs energy from its surroundings.
• Equilibrium: The state in a reversible reaction where the forward and reverse reaction rates are equal.
• Exothermic Reaction: A reaction that releases energy, typically as heat or light.
• Fermentation: Biochemical process converting glucose to ethanol and carbon dioxide by yeast enzymes.
• Filtration: A physical separation technique to distinguish soluble and insoluble substances based on solubility.
• Flammability: The likelihood of a substance igniting in the presence of fire.
• Formulation: Specific combinations of different compounds designed for particular purposes.
• Fractional Distillation: Technique for separating components of a mixture based on differing boiling points.
• Gas: A state of matter where particles move freely and can be compressed.
• Graphite: A form of carbon where each atom forms three bonds, resulting in layers that can slide.
• Greenhouse Gas: Gases that trap heat (infrared radiation) in Earth's atmosphere.
• Halogen: Highly reactive non-metals situated on the periodic table's right side.
• Homologous Series: Groups of organic compounds with the same functional group and similar chemical properties.
• Hydrocarbon: Compounds solely composed of carbon and hydrogen.
• Incomplete Combustion: Occurs in insufficient oxygen, producing carbon monoxide, a toxic byproduct.
• Intermolecular Forces: Attractive forces between molecules in a covalently bonded substance.
• Ion: An atom that has gained or lost electrons, carrying a charge.
• Ionic Bonding: The transfer of electrons from metals to non-metals, resulting in charged ions.
• Isotope: Variants of elements with the same number of protons but differing numbers of neutrons.
• Law of Conservation of Energy: States that mass in a reaction remains constant; mass of products equals mass of reactants.
• Life Cycle Assessment: An evaluation of environmental impacts of a product throughout its lifecycle.
• Liquid: A state of matter where particles can move, flow, and are incompressible.
• Mass Number: Total count of protons and neutrons in the nucleus of an atom.
• Melting Point: Temperature at which a solid transforms into a liquid.
• Metal: Elements on the left side of the periodic table that typically lose electrons to form positive ions.
• Mixture: A combination of different substances where each retains its own properties.
• Mole: The quantity of substance equal to its molecular mass in grams.
• Molecular Formula: Representation of the number and types of atoms in a molecule.
• Monomers: Small, reactive molecules that join in sequences to form polymers.
• Neutralisation: The reaction between an acid and an alkali producing a neutral solution (pH 7).
• Neutron: Neutral particle located in an atom's nucleus, contributing to mass.
• Noble Gas: Inert gases found on the right side of the periodic table, known for their lack of reactivity.
• Non-metal: Elements on the right side of the periodic table that typically gain electrons to form negative ions.
• Nucleus: Central part of the atom containing protons and neutrons.
• Orders of Magnitude: Comparisons of the scale or size of different values.
• Ore: Rock containing a significant amount of metal, making extraction economically viable.
• Oxidation: The process of losing electrons.
• Percentage Yield: A metric to express the efficiency of a reaction in terms of product yield.
• Periodic Table: A systematic arrangement of all known chemical elements.
• pH: A scale measuring how acidic or alkaline a solution is.
• Phytomining: Technique for extracting metals from low-grade ores using plants.
• Pipette: A laboratory tool used for measuring and transferring precise liquid volumes.
• Polymer: Large molecules formed from many repeating smaller units (monomers).
• Potable Water: Water deemed safe and suitable for drinking.
• Product: Material produced as a result of a chemical reaction.
• Reactant: Substance that undergoes a chemical change during a reaction.
• Reactivity Series: An ordered list of metals based on their reactivity.
• Reduction: The process of gaining electrons.
• Reversible Reaction: A reaction that can proceed in both forward and backward directions.
• Solid: A state of matter with fixed structure; particles vibrate around a fixed point.
• Titration: A method to determine the concentration of a solution through controlled addition of a titrant.
• Transition Metal: Elements in the middle of the periodic table; known for colored compounds and catalytic properties.
• Viscosity: A measure of a fluid's resistance to flow.